1. Field of the Invention
This invention relates to self-compensating, flexible edge, backup rolls for use in a rolling mill stand.
2. Description of the Prior Art
In the hot and cold rolling of strip metal, workers in the art continually seek improvements in both the quality of the strip produced by rolling and the cost effectiveness of the rolling operation. Among the factors that contribute to strip quality is the stability of the strip profile. Control of strip profile may, in turn, involve a variety of techniques and devices, applied both statically and dynamically.
A contribution to the overall improvement in strip profile control occurred with the discovery of the so-called "undesirable" contact zones between work rolls and backup rolls, outboard of the transverse profile of the strip, in a conventional four-high (and six-high) rolling mill. The effects of these undesirable zones are most pronounced when the strip width is less than the barrel length of the backup rolls. A solution to the undesirable contact zones problem was found in the use of stepped backup rolls or some other strip profile actuator that simulates that concept; e.g., axially shiftable rolls, both cylindrical and noncylindrical; axially shiftable sleeved rolls (see e.g. Japanese Patent No. 55-86606), etc.
As further work on strip profile control progressed, workers were led to appreciate the need for improved efficiency in the handling of work roll bending forces. This appreciation was manifested in attempts at softening the edges of the backup rolls to increase the overall dynamic flexibility of the roll system. A number of flexible edge roll systems have been proposed for sleeved rolls including those exemplified in U.S. Pats. Nos. 2,187,250; 3,097,590; and 4,599,770. Other rolls sleeve edge deflection schemes are shown in Japanese Patents Nos. 57-68206; 58-192104 and 59-54401.
More recent proposals involving flexible edge rolls are contained in U.S. patent application Ser. No. 746,376, now U.S. Pat. No. 4,683,744 filed June 18, 1985, entitled FLEXIBLE EDGE ROLL and U.S. patent application Ser. No. 795,577, filed Nov. 6, 1985, entitled SELF-COMPENSATING ROLL. The present invention is an improvement on the latter which discloses a backup roll having a sleeve shrunk fit on an arbor at its central portion so that the edge portions of the sleeve are free to deflect. Dynamic strip profile control is achieved with the self-compensating roll of U.S. Ser. No. 795,577, now U.S. Pat. No. 4,722,212 but a certain amount of inflexibility persists in the roll system by virtue of the rigid connection between sleeve and arbor at the center of the roll.